Well he wasn’t a very nice person by all accounts. He was a compulsive liar and borrowed or stole money from everyone he met. He was also a narcissistic megalomaniac which, although this led to him creating some very impressive music, doesn’t mean you’d want to sit down with him for a cup of tea. Or a biscuit.

So why has this man not been thrown long ago into music’s "sorry" bin? Why am I writing about him, and why are you reading? His music. It is astonishing and it set changes in motion that make him perhaps the most influential composer since Beethoven. Wagner’s operas—or music dramas as he called them—take us to strange places and times. They tend to be based on German history or folklore. There’s the cosy medieval world of The Mastersingers of Nuremberg. Think cobbled streets and illustrations from childhood story books. Or the ethereal Lohengrin and Parsifal, a world of knights and the Holy Grail. Or the extraordinary Tristan and Isolde: a torturous love affair derived from Celtic myths.

But it’s a series of four massive music dramas that were his crowning achievement. The Ring of the Nibelung (also known as "The Ring Cycle"). They’re The Rhinegold, The Valkyrie, Siegfried and The Twilight of the Gods. Forget Tolkien—this is the ultimate tale of a magical, terrible ring.

The cast includes Gods, nymphs, dwarves, heroes and heroines. And (spoiler alert) the most incredible ending with a fire and flood. It’s tricky to stage!

Wagner wrote the stories and texts for his music dramas and even had a hand in the stage and costume design. He even built the ultimate excess: a whole opera house just for their performance, in the town of Bayreuth.

In these music dramas, Wagner made so many innovations. Unlike most operas up until that point, they don’t start and stop. Each colossal act or chapter is one continuous piece of music. Wagner wanted to envelope us in his music and keep us suspended there. He also created the idea of a tune to represent a character or idea. This is called a "leitmotif." Here’s Siegfried:

Or the Gods and their kingdom of Valhalla. Or the heroine, Brünnhilde. Characters having a theme has been so prevalent ever since. Take film music, for example. John Williams’ Star Wars score has so many.

There’s something else important to say about Wagner’s music. Listen to this chord from the Prelude to Tristan and Isolde:

What musical key does that belong in? It doesn’t belong in any particular key. It’s ambiguous and strange. And with it Wagner asks a challenging question: Does music have to be in a key at all? Do you need to write a symphony, say, in C major or A minor?

Musicians have been searching for answers to these questions ever since. In fact a lot of music in the 20th century had no key, no chords, no scales — and this trend can be traced to Wagner.

If you can get over the man and his personal traits and beliefs, here is a towering genius of music history.

His megalomaniac tendencies gave us the greatest musical dramas ever to be staged. They carry us off into a mythical world and Wagner’s music cleverly sweeps us away by being present in every moment. And those clever little themes of leitmotifs keep the thread of the story going.

But perhaps most importantly, Wagner’s music shook off the idea that composers should be restricted to the old ideas of keys and chords and scales. This man — not the nicest man ever to have lived — set music free.